Checkpoint while developing sim_core unit test.

Task @T18 : Add and remove object while not running is working
properly. run_sim() is starting and time tracking is spot on, but
start_sim() does not seem to be returning properly (or at least
nothing else is moving after it's call. CPU is not bound.. in fact
utilization is very low at 50hz.
Merge branch 'sim_core' of github.com:fpstovall/nrtb_alpha into sim_core